1. Field of the Invention
The present invention relates to a sheet feeding apparatus that feeds a sheet to an image forming unit in an image forming apparatus and, in particular, to a drawing out mechanism of a sheet storage unit disposed in the sheet feeding apparatus.
2. Description of the Related Art
Conventionally, with a widespread image forming apparatus such as a copying machine, a printer, or a facsimile machine, sheets are fed one by one from a sheet feeding apparatus that stores sheets to an image forming unit and an image is formed thereon. With the sheet feeding apparatus, in general, the uppermost sheet is separated from the sheets stored in a sheet storage unit such as a sheet feeding cassette or a sheet feeding deck disposed in a main body of the sheet feeding apparatus. Then, the sheets are automatically fed one by one.
Recently, for the image forming apparatus, a sheet feeding apparatus is increasingly demanded to store a large amount of sheets and feed the sheets in response to a request to form an image to a large amount of sheets or a request to save the trouble for replenishing sheet. For example, an image forming apparatus is increasingly demanded to stack 1000, 2000, or more sheets to a sheet storage unit (such as a sheet feeding deck with a large capacity) and to then feed the sheets.
With the sheet feeding apparatus, the sheet storage unit that stores a large amount of sheets is greatly heavy. When drawing out the sheet storage unit from an apparatus main body for the purpose of sheet replenishment, sheet exchange, or status check of the sheet storage unit, a user completely draws out the sheet storage unit. Then, the user has to lift up the sheet storage unit and a burden of the user is greatly large. Preferably, the sheet storage unit can stop when the sheet storage unit is drawn out with a predetermined amount without completely detaching the sheet storage unit from the main body of the sheet feeding apparatus. On the other hand, the sheet storage unit can be detached from the apparatus main body for the purpose of exchange of parts therein.
Then, it is discussed that a sheet storage unit stops when drawing out the sheet storage unit with a predetermined amount at a usual drawing out time of the sheet storage unit, such as sheet replenishment or sheet exchange. Further, the sheet storage unit is fully detached from the apparatus main body if necessary. For example, Japanese Patent Application Laid-Open No. 11-301861 discusses that a stop member is disposed to abut on a sheet storage unit and stop the sheet storage unit before drawing out the sheet storage unit from an apparatus main body. Further, the stop member is rotated, thereby releasing the abutment state on the sheet storage unit, and the sheet storage unit is drawn out from the apparatus main body. Moreover, US Patent Application Publication No. 2009/0057975 discusses that a latch member that stops a sheet storage unit before the sheet storage unit is drawn out from an apparatus main body. Further, when drawing out the sheet storage unit from the apparatus main body, the sheet storage unit is obliquely lifted up to release the latch state with the latch member.
However, as discussed in Japanese Patent Application Laid-Open No. 11-301861, the following problem occurs in a configuration to release an abutment state between the sheet storage unit and the stop member with the rotation thereof when detaching the sheet storage unit from the apparatus main body. Specifically, with the configuration, when drawing out the sheet storage unit from the apparatus main body, the stop member is rotated simultaneously with an operation for drawing out the sheet storage unit. In the case where the sheet storage unit has a large capacity, the operability is low because a user must rotate the stop member while supporting the front side of the heavy sheet storage unit that stacks a large amount of sheets.
In addition, as discussed in US Patent Application Publication No. 2009/0057975, the following problem occurs in the configuration to draw out the sheet storage unit by obliquely lifting up the sheet storage unit to release the latch state with the latch member. In other words, with the configuration, when drawing out the sheet storage unit from the apparatus main body, it is required to lift up the sheet storage unit to release the latch state with the latch member and further draw out the sheet storage unit obliquely upward. The operability is also low because it is required to draw out the sheet storage unit with a large capacity while the sheet storage unit is lifting up obliquely.
With the configurations, the sheet storage unit can be detached from the apparatus main body if the sheet storage unit fully stacks sheets. Therefore, if the sheet storage unit with the large capacity is heavy beyond user expectation, there is a danger that the sheet storage unit can carelessly fall and a setting surface can be thus damaged or the sheet storage unit can be damaged.